Rotor bore and turbine rotor wheel/spacer heat exchange flow circuit

Abstract

In a turbine having closed-circuit steam-cooling passages about the rim of the rotor during steady-state operation, compressor discharge air is supplied to the rotor bore for passage radially outwardly into the wheel space cavities between the wheels and spacers. Communicating slots and channels in the spacers and wheels at circumferentially spaced positions enable egress of the compressor discharge air into the hot gas flow path. At turbine startup, cooling air flows through the closed-circuit steam passages to cool the outer rim of the rotor while compressor discharge air pre-warms the wheels and spacers. At steady-state, cooling steam is supplied in the closed-circuit steam-cooling passages and compressor discharge air is supplied through the bore and into the wheel space cavities to cool the rotor.

What is claimed is:  
     
       1. A turbine comprising: 
       a rotor having an axis and including a plurality of turbine wheels and spacers disposed alternately between the wheels, said wheels and spacers defining cavities therebetween, said turbine wheels mounting buckets for disposition in a hot gas path of the turbine, said wheels and spacers being secured to one another and defining a passage along the axis of the rotor for receiving compressor discharge air in communication with said cavities, said wheels and spacers having axially and circumferentially extending radially confronting flanges forming a rabbeted joint therebetween;  
       a first set of a plurality of circumferentially spaced slots carried by said wheel flanges and a second set of a plurality of circumferentially spaced slots carried by said spacer flanges, each said wheel and said spacer in axial confronting relation with one another being rotationally aligned to enable the flow of the compressor discharge air from said cavities through said aligned slots into said hot gas stream; and  
       closed circuit cooling steam passages along a rim of the rotor and into said buckets for steam cooling the buckets.  
     
     
       2. In a gas turbine having a plurality of turbine wheels and spacers disposed alternately between the wheels, said wheels and spacers being secured one to the other to form a turbine rotor having a central axial passage, said wheels and spacers defining cavities therebetween, the wheels mounting buckets for disposition in a hot gas path of the turbine, a method of operating the turbine comprising the step of, during startup, supplying compressor discharge air along said axial passage and into said cavities between the wheels and spacers to heat the wheels and spacers, supplying cooling steam along said rotor and into said buckets for cooling the buckets during steady state operation, and supplying compressed discharge air along said axial passage and into said cavities to cool the rotor during steady state operation. 
     
     
       3. A method according to  claim 2  including flowing the compressor discharge air from the cavities into the hot gas path. 
     
     
       4. A method according to  claim 2  including forming rabbeted joints between the wheels and spacers defining the radial outermost extent of said cavities and providing metering passages through said rabbeted joints at circumferentially spaced positions about the joints for flowing the compressor discharge air from the cavities into the hot gas path. 
     
     
       5. A method according to  claim 2  including providing closed circuit steam cooling passages along a rim of the rotor and in communication with interior portions of said buckets for flowing cooling steam to said buckets during steady state operation, and during start-up, supplying cooling air along said steam cooling passages to cool the buckets during start-up.